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Thyristors are electrotechnical components and so-called solid-state semiconductors consisting of four alternating layers (N and P materials). Their mode of operation is clearly similar to the functionality of diodes. Both components have a similar circuit diagram and allow voltage to flow in one direction and block it in the other. While a simple diode has only two connections, the anode and cathode, a thyristor also has a gate connection. This has the task of controlling the thyristor, since the current flow is initially blocked in both directions in the idle state. By sending a small current pulse to the gate connection, a thyristor “ignites” and is put into the conductive state.

Overall, thyristors add the possibility of controllability to the functionality of simple diodes. The control is done via the already mentioned gate connection. The thyristor is switched to its conductive state by an ignition pulse at the gate. This continues until the current falls below a defined holding current. The thyristor must then be ignited anew to become conductive again.

Overvoltage protection by thyristors

Thyristors are used, among other things, in devices for overvoltage protection. Here, for example, it serves as an active overvoltage protection component that ensures that an overvoltage pulse is dissipated against ground potential. Such circuits are called clamp or crowbar.

Further areas of application for thyristors are motor controls, power controls or various applications in high-performance pulse technology.